Valves for use in high pressure lines must meet certain high standards. It is necessary in many petrochemical industry applications, for example, that the valves be "fire-safe" so that in the event of a fire in a processing plant, the valves will remain closed to stop the flow of any fluids which may be hazardous if exposed to open flames. This means that the valve must have metal-to-metal contact and must not use elastomeric or heat decomposable sealing surfaces. Eccentric ball type valves and valves utilizing segments of spheres have been proposed for high pressure lines. However, those having metal-to-metal seating engagement with essentially quarter-turn operating motion have not found wide acceptance due to the extremely fine manufacturing tolerances required for positive closure of such valves. Thus, for example, it is necessary, with an eccentric ball type valve, to provide that the spherical valve member engages the seat in only one angular position. Thus, as the valve is opened, the spherical valve member moves out of engagement with the seat and out of engagement with the wall of the valve chamber for ease in opening and closing. However, in order to do this and seat properly for complete closure, it is necessary that all of the valve components related to seating be machined to such fine tolerances that mass production, for the most part, has not been feasible.